Nanometer thick magneto-optical iron garnet films

Here we demonstrate nanometer thick iron garnet films suitable for the magneto-optical applica-tions. Bismuth-substituted iron garnet films of compositions Bi_1Y_2Fe_5O_12 and Bi_1Tm_2Fe_5O_12 deposited on gadolinium gallium garnet substrate are fabricated and characterized. Their thicknesses range from 2 to 10 nm, which corresponds to just a few crystal lattice constants. Faraday rotation of the nanofilms reaches 29.7 deg/μm at 420 nm which is comparable and even a bit better than single crystal micrometer thick films of similar composition. The film surface morphology by atomic force microscopy gives root mean square (RMS) roughness of the nanofilms as small as 0.13 nm that is also similar to the RMS of single crystal micrometer thick films. The Bi_1Tm_2Fe_5O_12 films demonstrate effective uniaxial anisotropy. These all make the fabricated nanofilms very promising for their po-tential applications in magneto-optical devices and quantum technologies.